The specific aim of the project is to determine why cell-free preparations from old organisms have a reduced ability to synthesize protein. Preparations from young and old Turbatrix aceti, a free-living nematode will be used as a model system. In this organism, protein synthesis decreases steadily with age. Thus, a convenient, homogeneous system is available for study on a comparative basis. A search will be conducted to determine what component is deficient in old preparations. The functional ability of "old" elongation and initiation factors, mRNA, tRNA-amino synthetases, RNAse, RNA polymerase and ribosomes will all be examined. The turnover of ribosomes from young vs. old organisms will be compared. Exchange of various "young" and "old" constituents in the protein synthesizing system will provide a useful aid in locating the deficient component. The findings from the nematode system will be applied to studies of aging rodents. A longer term goal of the work is to determine whether regulation of protein synthesis in different metabolic situations is controlled in an identical way. Therefore, cell-free systems will be studied under conditions other than aging, where protein synthesis has been slowed. Examples of such conditions include cessation of growth in T. aceti by removal of a growth requirement (heme) from the medium and fasting in rats. From the results obtained, it is hoped to identify the lesion which causes cell-free protein synthesis to decline in old animals and to determine whether or not control of the rate of protein synthesis under all conditions is mediated by a single mechanism or by multiple factors.